Demyelinating Diseases — MCQs
Which test is most useful in diagnosing a clinically occult lesion in multiple sclerosis?
All of the following are morphological neurological complications of measles except
Investigation of choice for multiple sclerosis
Which of the following drugs is preferred in the management of primary progressive multiple sclerosis?
A patient has had recurrent optic neuritis bilaterally with transverse myelitis. Visual acuity in right eye is 6/60 and left eye is 6/18. Patient showed a 50% response to steroids. Diagnosis is?
False regarding Alzheimer's disease (AD) is:
A muscle biopsy shows type 1 fiber atrophy and increased internal nuclei on histology. Which additional finding on light microscopy would be most specific for myotonic dystrophy?
Loss of striatal fibres in caudate nucleus is associated with?
What is the histological appearance of the brain in Creutzfeldt-Jakob disease?
An elderly man has become progressively unable to live independently over the past several years, requiring assistance with daily activities. He has no motor or sensory deficits on physical examination, but is unable to give the current date or state his location. At autopsy, a large superficial left parietal lobe hemorrhage is found, along with numerous neocortical neuritic plaques and neurofibrillary tangles in the brain. Which mechanism is most likely responsible for his disease?
Demyelinating Diseases Indian Medical PG Practice Questions and MCQs
Question 1: Which test is most useful in diagnosing a clinically occult lesion in multiple sclerosis?
- A. Evoked potentials for diagnosing clinically occult lesions in multiple sclerosis
- B. CT scan for large hemispheral strokes
- C. Evoked potentials for brainstem involvement in stroke
- D. MRI for detecting white matter lesions in multiple sclerosis (Correct Answer)
Explanation: **MRI for detecting white matter lesions in multiple sclerosis** - **MRI** is the most sensitive imaging technique for detecting **white matter lesions** characteristic of multiple sclerosis, especially **clinically occult lesions** that do not cause obvious neurological symptoms [1]. - It can identify both new and enhancing lesions (indicating active inflammation) and older, non-enhancing lesions, which is crucial for diagnosis and monitoring disease progression according to the **McDonald criteria**. *Evoked potentials for diagnosing clinically occult lesions in multiple sclerosis* - **Evoked potentials** (e.g., visual, brainstem, somatosensory) can detect slowed conduction in specific neurological pathways, indicative of demyelination, even if the patient is asymptomatic [2]. - While useful for demonstrating dissemination in space if clinical signs are limited, they are **less sensitive than MRI** for detecting the full burden of clinically occult lesions across the entire CNS. *CT scan for large hemispheral strokes* - A **CT scan** is primarily used for rapid detection of **acute hemorrhage** or **large ischemic strokes** due to its speed and availability [1]. - It is **poorly sensitive** for detecting the demyelinating plaques of MS and would not be the primary diagnostic tool for occult lesions in this context. *Evoked potentials for brainstem involvement in stroke* - **Evoked potentials** can assess the integrity of brainstem pathways, and while useful in certain neurological conditions, they are **not the primary diagnostic test for stroke**. - **Neuroimaging (CT or MRI)** is the gold standard for diagnosing stroke and identifying brainstem involvement.
Question 2: All of the following are morphological neurological complications of measles except
- A. SSPE
- B. Encephalitis
- C. Optic neuritis (Correct Answer)
- D. Transverse myelitis
Explanation: ***Optic neuritis*** - **Optic neuritis** is not considered a typical *morphological* neurological complication directly caused by measles virus infection itself. - While visual disturbances can occur with CNS complications, **optic neuritis** itself is more commonly associated with demyelinating diseases like **multiple sclerosis** [1]. *SSPE* - **Subacute sclerosing panencephalitis (SSPE)** is a rare but devastating *morphological* neurological complication of measles, caused by a persistent measles virus infection in the brain [2]. - It leads to progressive **neurodegeneration** with characteristic inclusion bodies and gliosis. *Encephalitis* - **Measles encephalitis** is an acute *morphological* inflammation of the brain parenchyma, which can be either directly viral or post-infectious (acute disseminated encephalomyelitis - ADEM) [1]. - It often presents with seizures, altered consciousness, and focal neurological deficits, indicating structural brain involvement. *Transverse myelitis* - **Transverse myelitis** is a recognized *morphological* neurological complication following measles, characterized by inflammation across one section of the **spinal cord** [1]. - This leads to motor weakness, sensory loss, and autonomic dysfunction below the level of the lesion.
Question 3: Investigation of choice for multiple sclerosis
- A. CT
- B. MRI (Correct Answer)
- C. USG
- D. PET
Explanation: ***MRI*** - **Magnetic Resonance Imaging (MRI)** is the investigation of choice for **multiple sclerosis** due to its superior ability to visualize **demyelinating plaques** in the brain and spinal cord. - It can detect both **new and old lesions**, crucial for diagnosis and monitoring disease progression, according to the **McDonald criteria**. *CT* - **Computed Tomography (CT) scans** are generally less sensitive than MRI in detecting the subtle **demyelinating lesions** characteristic of multiple sclerosis. - While it can sometimes show larger lesions, it often misses smaller or early-stage plaques, making it less suitable for initial diagnosis. *USG* - **Ultrasound (USG)** is primarily used for visualizing soft tissues and vascular structures, not for detailed imaging of the brain or spinal cord parenchyma. - It has no role in the diagnosis or monitoring of **multiple sclerosis**. *PET* - **Positron Emission Tomography (PET) scans** are used to assess metabolic activity and perfusion, often in oncology or certain neurological disorders like Alzheimer's or Parkinson's disease. - It is not routinely used for the diagnosis of **multiple sclerosis**, as it does not clearly visualize the **demyelinating lesions**.
Question 4: Which of the following drugs is preferred in the management of primary progressive multiple sclerosis?
- A. Natalizumab
- B. Ocrelizumab (Correct Answer)
- C. Alemtuzumab
- D. Fingolimod
Explanation: ***Ocrelizumab*** - **Ocrelizumab** is the first and only FDA-approved disease-modifying therapy for **primary progressive multiple sclerosis (PPMS)**, demonstrating a reduction in disability progression. - It is a **monoclonal antibody** that selectively targets CD20-positive B cells, believed to play a critical role in the pathogenesis of MS. *Natalizumab* - **Natalizumab** is approved for **relapsing-remitting multiple sclerosis (RRMS)**, not primary progressive MS [1]. - It works by blocking the migration of immune cells into the **central nervous system**, but carries a risk of **progressive multifocal leukoencephalopathy (PML)**. *Alemtuzumab* - **Alemtuzumab** is used for **relapsing forms of MS**, particularly in patients who have had an inadequate response to other MS drugs [1]. - It is known for its durable efficacy but also its significant side effects, including **autoimmune conditions** and **infusion reactions**. *Fingolimod* - **Fingolimod** is an oral medication approved for **relapsing forms of MS**, but not for primary progressive MS [1]. - It acts by trapping lymphocytes in the **lymph nodes**, preventing them from entering the central nervous system.
Question 5: A patient has had recurrent optic neuritis bilaterally with transverse myelitis. Visual acuity in right eye is 6/60 and left eye is 6/18. Patient showed a 50% response to steroids. Diagnosis is?
- A. Posterior cerebral artery stroke
- B. Neuro-syphilis
- C. Neuromyelitis Optica (Correct Answer)
- D. Subacute combined degeneration of the spinal cord (SACD)
Explanation: ***Neuromyelitis Optica*** - The combination of **recurrent bilateral optic neuritis** and **transverse myelitis** is highly characteristic of Neuromyelitis Optica (NMO). - NMO is an autoimmune inflammatory disorder of the central nervous system that predominantly affects the **optic nerves** and **spinal cord** [1]. *Posterior cerebral artery stroke* - A **posterior cerebral artery stroke** typically causes sudden visual field defects (e.g., homonymous hemianopsia) or memory deficits, but not recurrent optic neuritis or transverse myelitis. - **Stroke** is an acute vascular event, whereas the symptoms described are recurrent and inflammatory in nature [1]. *Neuro-syphilis* - **Neuro-syphilis** can involve the optic nerves and spinal cord, but the pattern of recurrent bilateral optic neuritis and transverse myelitis is less typical. - Diagnosis usually involves serological tests (VDRL, RPR) and CSF analysis for **treponemal antibodies**. *Subacute combined degeneration of the spinal cord (SACD)* - **SACD** is caused by **vitamin B12 deficiency** and primarily affects the posterior and lateral columns of the spinal cord, leading to gait ataxia, paresthesias, and weakness [1]. - It does not typically cause **recurrent optic neuritis** or the specific pattern of transverse myelitis described.
Question 6: False regarding Alzheimer's disease (AD) is:
- A. Number of neurofibrillary tangles is associated with the severity of dementia
- B. Number of senile (neuritic) plaques correlates (increases) with age
- C. Presence of tau protein suggest neurodegeneration
- D. Extracellular inclusion (lesion) can occur in the absence of intracellular inclusions to make pathological diagnosis of AD (Correct Answer)
Explanation: ***Extracellular inclusion (lesion) can occur in the absence of intracellular inclusions to make pathological diagnosis of AD*** - A definitive pathological diagnosis of **Alzheimer's disease** requires both the presence of **extracellular amyloid plaques** and **intracellular neurofibrillary tangles** [1]. - Neither inclusion type alone is sufficient for the diagnosis, as amyloid plaques can be found in non-demented elderly individuals [1]. *Number of neurofibrillary tangles is associated with the severity of dementia* - The **density and distribution of neurofibrillary tangles** (NFTs) directly correlate with the severity of cognitive impairment and **dementia** in AD [1]. - Tangles are composed of hyperphosphorylated **tau protein** and disrupt neuronal function, leading to neurodegeneration [2]. *Number of senile (neuritic) plaques correlates (increases) with age* - The accumulation of **senile (neuritic) plaques**, composed primarily of **beta-amyloid protein**, generally increases with age, even in cognitively normal individuals [1]. - While plaques are a hallmark of AD, their mere presence is not always diagnostic of clinical dementia [1]. *Presence of tau protein suggest neurodegeneration* - The presence of **hyperphosphorylated tau protein**, especially when forming **neurofibrillary tangles**, is a strong indicator of **neurodegeneration** [2]. - **Tauopathy** is a key pathological feature in AD and other neurodegenerative diseases [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1294. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722.
Question 7: A muscle biopsy shows type 1 fiber atrophy and increased internal nuclei on histology. Which additional finding on light microscopy would be most specific for myotonic dystrophy?
- A. Nemaline rods
- B. Ragged red fibers
- C. Ring fibers (Correct Answer)
- D. Central cores
Explanation: ***Ring fibers*** - The presence of **ring fibers** (annular fibers with peripherally arranged myofibrils forming a ring around the fiber core) is a **classic and highly specific** histological finding for **myotonic dystrophy type 1 (DM1)**. - Ring fibers are seen in **25-50% of cases** and result from abnormal myofibrillar architecture with peripheral displacement of myofibrils. - Combined with type 1 fiber atrophy and increased internal nuclei, ring fibers provide strong confirmation of myotonic dystrophy [1]. *Nemaline rods* - **Nemaline rods** (rod bodies) are characteristic protein aggregates composed of Z-line material found in **nemaline myopathy**, a distinct congenital muscle disorder. - They appear as dark red structures on Gomori trichrome stain and are not a feature of myotonic dystrophy. *Ragged red fibers* - **Ragged red fibers** are a hallmark of **mitochondrial myopathies**, indicating abnormal subsarcolemmal accumulation of mitochondria seen on modified Gomori trichrome stain. - These are definitively associated with primary mitochondrial dysfunction (e.g., MELAS, MERRF), not myotonic dystrophy. *Central cores* - **Central cores** are areas within muscle fibers devoid of oxidative enzyme activity, characteristic of **central core disease** (autosomal dominant RYR1 mutations). - This finding is not expected in myotonic dystrophy and represents a different congenital myopathy. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 732-733.
Question 8: Loss of striatal fibres in caudate nucleus is associated with?
- A. Hemiballismus
- B. Huntington's disease (Correct Answer)
- C. Charcot-Marie-Tooth disease
- D. Parkinson's disease
Explanation: ***Huntington's disease*** - This neurodegenerative disorder is pathologically characterized by **atrophy of the striatum**, particularly the **caudate nucleus** [1]. - The loss of striatal neurons, especially medium spiny neurons, leads to the characteristic **chorea** and cognitive decline [1]. *Hemiballismus* - Characterized by **unilateral, violent, flinging movements** of the limbs. - It is typically caused by a lesion in the **subthalamic nucleus**, not the caudate nucleus. *Charcot-Marie-Tooth disease* - A group of inherited disorders that affect the **peripheral nerves**, leading to muscle weakness and sensory loss. - This condition does not involve the degeneration of the striatal fibers in the caudate nucleus. *Parkinson's disease* - Primarily caused by the degeneration of **dopaminergic neurons** in the **substantia nigra pars compacta**. - While it affects the basal ganglia circuitry, its primary pathology is not the loss of striatal fibers in the caudate nucleus but rather a **dopamine deficiency**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1299-1300.
Question 9: What is the histological appearance of the brain in Creutzfeldt-Jakob disease?
- A. Neuronophagia
- B. Micro abscess
- C. Demyelination
- D. Spongiform changes (Correct Answer)
Explanation: ***Spongiform changes*** - The hallmark histological feature of **Creutzfeldt-Jakob disease (CJD)** is **spongiform degeneration**, characterized by vacuolation of neuronal cell bodies [1]. - It results in a **spongy appearance** of the affected brain regions, particularly in the **cerebral cortex** and **basal ganglia** [1]. *Neuronophagia (can occur in various contexts, not specific to CJD)* - Neuronophagia refers to the phagocytic activity involving **dying neurons**, which can occur in various conditions but is not a defining feature of CJD [2]. - It indicates the presence of **inflammation** or a response to neuronal injury rather than specific changes seen in CJD. *Demyelination (associated with multiple sclerosis)* - Demyelination is primarily associated with conditions like **multiple sclerosis** and is characterized by loss of **myelin sheaths** around neurons. - This is not related to CJD, which involves **prion protein accumulation** and subsequent neuronal degeneration. *Micro abscess (indicative of bacterial infections)* - Micro abscesses indicate localized collections of **pus** typically seen in **bacterial infections**, which is incongruent with the pathophysiology of CJD. - In CJD, there are no signs of **inflammation** or **neutrophilic infiltration** associated with abscess formation [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1284-1286. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1255-1256.
Question 10: An elderly man has become progressively unable to live independently over the past several years, requiring assistance with daily activities. He has no motor or sensory deficits on physical examination, but is unable to give the current date or state his location. At autopsy, a large superficial left parietal lobe hemorrhage is found, along with numerous neocortical neuritic plaques and neurofibrillary tangles in the brain. Which mechanism is most likely responsible for his disease?
- A. Conformational change in the prion protein (PrP)
- B. Dopamine deficiency
- C. Expansion of polyglutamine repeats
- D. Aggregation of Aβ peptide (Correct Answer)
Explanation: ***Aggregation of Ab peptide*** - The presence of **neocortical neuritic plaques** containing **Aβ (Amyloid beta) peptides** is indicative of Alzheimer's disease, where peptide aggregation is a crucial mechanism [1,2]. - This aggregation leads to **neurodegeneration** and associated symptoms, aligning with the patient's cognitive decline and sudden coma [2]. *Dopamine deficiency* - Primarily associated with **Parkinson's disease**, which typically presents with **motor deficits** such as tremors and rigidity, unlike this patient's purely cognitive symptoms. - Dopamine deficiency does not explain the findings of **neurosenile plaques** and **tangles** in the context of an 86-year-old male. *Conformational change in the prion protein (PrP)* - This mechanism relates primarily to **prion diseases** like Creutzfeldt-Jakob disease, characterized by rapid neurological decline and distinctive histopathological findings. - There is no evidence of **prion-like degeneration** or **spongiform changes** noted in this patient's brain autopsy findings. *Expansion of polyglutamine repeats* - This is primarily associated with **Huntington's disease**, marked by **chorea and cognitive decline**, rooted in basal ganglia dysfunction, which is not applicable here. - The findings in this patient relate more to **Alzheimer's disease** pathology than polyglutamine expansion disorders. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1290-1294.
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